Long-term natural history of thyroid peroxidase antibodies in a population-based cohort: Findings from 18 years of follow-up in Tehran Thyroid Study (TTS)

This is the first and longest study worldwide that demonstrated a persistent rise in TPOAb positivity across five repeated measurements in an iodine-sufficient population, driven by female sex, age <40, and TSH ≥5 mU/L, which is projected to reach 21.04% in 2030. Trajectory patterns of TPOAb showed that the majority of participants had consistently low-stable levels of TPOAb.